1. Field of the Invention
The present invention relates generally to an improved design for an internal heat exchange fin. In particular, the present invention relates to a simple spring-loaded fin design which may be placed easily into, and fixed within, an extruded container or vessel. A particularly important application of this invention is directed to a storage containers for accommodating a hydrogen absorbing alloy.
2. Background Art
In recent years devices such as fuel cells, heat pumps, and motor vehicles have been, and continue to be developed which rely upon hydrogen gas as an energy source. Hydrogen gas typically is supplied to these devices utilizing a hydrogen absorbing alloy which can reversibly absorb and desorb hydrogen. Furthermore, the alloy is usually accommodated in the form of a powder or molded body disposed within a containment vessel.
It is known that in order to provide a stable, reversible supply of hydrogen gas from the hydride alloy it is necessary to also provide a means for introducing and removing heat to the alloy. Various methods have been proposed in the art for accomplishing this task. Most of these methods generally conform either to burying an exchange tube 102 with a plurality of heat exchange fins 110, attached thereto, into a volume of the hydride alloy 104, as in FIGS. 1A and 1B, or contacting the alloy volume with a series of plates 201 attached to an exterior surface 202 which may be heated or cooled with one of more exchange tubes 203, as in FIG. 2. Examples of both of these approaches are described in U.S. Pat. Ser. Nos. 5,797,269, 4,165,569 and 4,819,718.
Structures heretofore used for holding the hydride material and storing the hydrogen have typically included a storage container having a plurality of conduits running through the container. The hydride material is placed in the container and a heat exchange medium passed through the conduits either to cool the hydride material, when storing the hydrogen, or to heat the hydride material, when releasing the hydrogen. One of the problems with this type of structure is that, because of the geometry of the conduits relative to the hydride material, some of the hydride material is disposed in locations too far from the conduits to readily absorb or release hydrogen. That is, because the heat transfer path between the heat exchange medium and some hydride material is long, either the hydrogen will not be absorbed or released from such material, or the time required for such absorption or release is longer than desired. Of course, increasing the number of conduits helps but this also reduces the space available in the container for holding the hydride material and increases the weight and cost of construction of the container. What is needed, therefore, is a heat transfer structure which can contact a greater percentage of the reactor bed media surface area across a greater cross section of that reactor bed.
Heat exchangers of varying designs are well known in the art, particularly tube and plate designs wherein a tortuous flow path is imposed on a circulating fluid. As noted, such structures, if they are to be efficient, are generally comprised of a substantial number of elements making them difficult and expensive to manufacture. Furthermore, application of this type of heat exchanger typically requires penetrating the containment vessel wall in order to introduce a heating source since the exchange elements themselves are not necessarily in thermal contact with the container wall which would allow for conductive heat transfer through that wall.
It is therefore an object of this invention to provide a simple internal element to function as a heat transfer xe2x80x9cfinxe2x80x9d for a heat exchanger.
It is a further object of this invention to provide an internal element which may be set in place within a vessel such that it remains mechanically self-supporting and further such that it provides effective thermal coupling between itself and the vessel wall.
It is yet another object of this invention to provide an internal heat transfer element which will not buckle when constrained by a wall.
It is an object of the present invention to provide hydride storage and heat exchanger structures adapted to enable the efficient and rapid absorption and release of hydrogen by hydride material contained in the structure.
It is also an object of the present invention to provide such structures in which a heat exchange medium may be applied thereto to uniformly and evenly heat or cool the hydride material.